Overview

For the past decade the energy consumption of data centers has increased quite substantially. For the year 2014 the world wide power consumption was estimated at 38.84 GW. The aggregated power consumption of all HPC systems in the November 2014 Green500 list was 592.31 MW (which does not include the data center cooling overhead). According to DataCenterDynamics Intelligence the average data center Power Usage Effectiveness (PUE) world wide was in the range of 1.81 and 2.0 for 2013. An Uptime Institute survey showed an average PUE of 1.65 for 2013. Using the average of both surveys (1.78, which is most likely very optimistic) 17GW of total data center power consumption was spend on the infrastructure needed to run and cool the IT systems. Therefore, the reduction of energy consumption and the possible reuse of waste heat becomes increasingly important issues in the design and operation of large data centers. If we talk about data center energy efficiency we need to talk about cooling technologies. In the past this was not a strong focus since all data centers used air cooling. Today, many super-computing data centers use a combination of different cooling technologies but there exists a lack of knowledge regarding the energy efficiency of the different cooling infrastructures and their efficient operation. Current data center infrastructures are, like traditionally air cooling, designed and optimized for the maximum possible load. But this peak load is rarely seen in production.

Additionally, previous systems showed not a big difference between idle and load power consumption. But advances in energy efficient processor architectures have increased the variability in the energy consumption of HPC systems quite substantially (for example, SuperMUC [Number 14 on Top500 list from 11/2014] has an idle power consumption of 800kw, an average power consumption of 2.2 -2.4 MW in normal operation, and a maximum power consumption of 3.6MW achieved during Linpack benchmark). This increased variability coupled with the conservative infrastructure design creates great challenges for running the data center infrastructure efficiently.

But the combination of this new load variability and the use of new cooling technologies in the data center (chiller-less cooling) provides an opportunity to increase the energy efficiency of the data center.
This workshop will highlight challenges and solutions associated with the increase of energy efficiency in HPC data centers and the reuse of waste heat, and will highlight some opportunities where data centers naturally connect with a smart city idea.